Conventionally, this kind of shelf apparatus, as found in, e.g., Japanese Utility Model publication No. 18750/1986, comprises wheel rails having a number of wheels and disposed in a plurality of vertically spaced stages in a frame, with the direction of transport (slide) being inclined. According to this conventional shelf apparatus, a load fed to on the upper region of the slope slides down on the wheels until it is stopped by a stopper installed at the lower end; thus, successively fed loads are stopped for storage by their respective preceding loads. Loads which are stored are taken out as needed from the lower region of the slope and the vacancies thus formed are filled in that succeeding loads slide down to fill such vacancies. In this conventional example, putting in and out of loads is manually effected, but in a large-sized shelf apparatus, for example, a forklift cart is used to carry in and out loads.
According to the conventional shelf apparatus as described above, transport of loads is effected by slide movement utilizing the free rotation of wheels: thus, if the free rotation of wheels fail to take place smoothly or if there is a variation in the weight of loads, the slide movement does not take place positively, lacking in reliability. Further, from the standpoint of frictional resistance, there are some pallets which cannot be employed because of the material of which they are made. It is conceivable that this can be coped with by providing a sufficient angle of inclination; however, a large angle of inclination results in the slide speed becoming high and varying, so that when a load is stopped by a stopper, a high shock is exerted; thus loads become unstable. Also, the dead space for the slope increases, resulting in inefficient storage.